Heat exchanger



Jan. 16, 1923. l 1,142,783. C. F B RA U N.

HEAT EXCHANGER.v Y FILED SEPLS. 1919.

Z SHEETS-SHED 2.

INVENTOR @wml Www/u2@ A TTORNE YS Patented dan. 16', 1923.

amava casina.

CARL F. BRAUN, F SA FRANCISCO, CALIFORNIA.

HEAT EXCHANGER.

Application led September 3, 1919. Serial No. 321,450.

To all whom it mag/concern: Be it known that I, CARL F. BRAUN, a citizenof the United States, residing at the city and county of San Franciscoand State of California, have invented new and useful Improvements inHeat Exchangers, of which the following is a specification.

This invention relates to a heat exchanger. In surface heat exchan ersmaximum efliciency is obtained by pro ucing a maximum heat transferaccompanied by a minimum friction loss and as these two factors are atvariance with each other, it has been an important problem to designheat exchangers which will comply with the specifications ofinstallation engineers. This is particularly true when two fluids areinvolved and one or 4both of the fluids'are very viscous. In this case,it is necessary to prodnce the maximum heat transfer by increasing theamount of turbulence thus producing satisfactory convection currents forthe transfer of heat, in addition to that transferred by conduction. Itwill readily be seen that by increasing the turbulency of the viscousfluid the friction loss will be increased and it is the principal objectof the present inventionto provide a heat exchanger` structure whichwill in this manner produce a maximum turbulence accompanied by aminimum friction loss.

The present invention is concerned with a structure embodying the use ofan enclosing shell, having inlet and outlet openings for two uids atoneend thereof and being `further arranged with longitudinally extendingcompartments, through which one ofl the fluids may flow and whichcompartments are equipped 'with circulating tubes through which theother liquid may-flow, the com- 40 partments being further separated by`a plurality of transversely extending baie members formed with a seriesof orifices systemaitically spaced thereover .and preferably arranged instaggered .relation to each other 45 when the adjoining baflief platesare considered. l j f The invention is illustrated by way of exf amplein thev accompanying drawings, in 'which- 5e Fig. 1 is a view inlongitudinal :section linto two equal compartments. One of these showingone form of the present invention and the arrangement of the baiieplates therein.

Fig. 2 is a view in end elevation, disclosing the inlet andoutletconnections of the heat 5e exchanger.

Fig. 3 is an enlarged view in vertical section, as seen on the line 3-3of Fig. 1, more particularly disclosing the baffle-plates and thearrangement of the circulating tubes and the baille-plate perforations.

Fig.- 4c is an enlarged fragmentary view in section through one of thedistributing openings to the baflie plate.

Fig. 5 is a fragmentary view in section and elevation showing thestaggered relation of the openings in adjacent baffle plates.

In the drawings a heat exchanger is illustrated, the generalconstruction of which is more fully disclosed in my copending aplication, entitled Heat exchanger, filed arch 13th, 1919, and bearingthe Serial Number 282,258 which has matured into Patent No. 1,376,135,April 26, 1921.2 n this structure. the tubular shell 10 is provided,having a continuous central passageway of uniform dimension extendingthroughout the length thereof. The opposite ends of the shell areprovided with bolting flanges 11 and 12. A cap 13 is fitted against oneend of the shell and bolted to the flange 12 by means of' bolts 14. Thiscap has an interior bore agreeing in dimensions with the main passagewayA`through the shell. The opposite end of the shell is provided with anextension drum 15 bolted to the ange 11 by bolts 16. This drum is formedwith an interior bore of slightly smaller diameter than the shellpassageway and is mounted concentric withthe longitudinal axis of theshell. The outer end of the drum is normally closed by a removable coverplate 17. A central vertical partition 18 passes through the drum 15 anddivides the cylindrical interior thereof compartments is fitted with afluid inlet pipe 19 and the other with a fluid outlet pipe 20, as .moreclearly shown in Fig. 2 of the drawin s.

ormed integral with the opposite sides of .1

a circumscribing chamber 23, which has an annular 3opening 24 incommunication with the interior bore of the shell. The centralpassageway through the shell 10 is divided into two longitudinalcompartments 23 and 24', by means of a pluralit of longitudinallyextending-aligned partition members 25.

These members are arranged to eX- tend substantially the full length ofthe shell and are secured upon a central tie rod 26.

One end of this rod is fastened into a tube sheet27 while the other endis secured through the last of the transverse baffle members 28,

in order that the various partition sections` 25 and baffle members 28may be replaced or removed as convenience requires. The baille-platesare interposed between the par tition sections 25 and are thusspacedequal distance from' each other, substantially throughout the length ofthe tubes, allof them being secured together by the centralrod 26 andthe nut 29. It is'intended that atwo-way flowwill take place.longitudinally of the shell and for this reason the series of partitionmembers are interposed between each of the baffle plates 28, and alsobetween the end baffle plate 28 and the tube sheet 27. This will insurea two-way flow throughout the length of the shell and around through cap13. This space affords'communication between the two compartments 23 and24 of the shell and insures complete circulation of the viscous fluidfrom the inlet connection .21 to the outlet connection 22 along a pathof travel twice the length of the shell. y y y Mounted within the cap`is a floating tube sheet 30. Thissheet is of smaller dimensions thanthe inside bore of the cap 13, and thus allows free circulation df theviscousl fluid1 therearound andat the same time permits the cap 33 to bereadily removed therefrom.

The tube sheets 27 and 30 are thus disposed at opposite ends of thestructure and are adapted to receive a plurality of circulating tubes31. The exact arrangement of these tubes is more particularly indicatedin Fig. 3 of the drawings, where it will be seen that they aresystematically disposed upon opposite sidesof the partition members 25and will insure that a substantiallyuniform coolin action will beproducedvby the viscous uid as it passes around the pipes and throughthe compartments 23 and 24. The tubes all communicate with the drum 1 5at one end and at the opposite end are in communication with each otherby means of the tube sheet cap 33, which'is secured o'ver the end ofthefloating tube sheet 30, as shown in Fig. 'Attentionis directed tothefact that.

be readily attached to will be seen that two sets of perforations arethe end 'of the tube nest carrying cap 33 pro' jects a suflicientdistance'beyond the shell flange 12 to ensure that-when the shellcap 13is removed the cap 33 and the tube sheet to lwhichit is attached willbeentirely uncovered and accessible so that the cap33 may the tube sheetfrom the opposite side thereof. V

By reference t0 Fig. 3 of the drawings, it

formed through the baille-plates. One set of perforations is designed toreceive the tubes 31, while the other set is provided to permit acirculation of the viscous fluid through the baille-plate. This secondset of perforations is indicated. at32I and will be seen to be of suchdimensions as to overlap the perforations for the tubes and thus form acentral opening between certain of the tubes and partially around theirexterior surfaces. I f

. At the vpoint of perforation, it will thus be seen vthat each of thepassageways 32 has a sidewall made up of a part of the surface .of threeof-the tubes 31 and a portion of the baffle-plate intervening betweenthese tubes. The baille-plate portion of the perforations may be cutaway as more clearly shown in Fig. 4 to form what is commonly known as africtionless orifice, although when thin gage metal is used the'sameresult will be obtained without making the counterbore. These openingsare thus provided with substantially knife-shaped edges upon the sidesof the baflleagainst which the fluid is flowing. By comparison of thetwo halves of the baffle-plate shown in Fig. 3, it will be seen that thecirculating orifices 32 are staggered in relation to each other and thatby revers ing the alternate baille-plates throughout the length of theshell, the space dened by three of the tubes will be in alternatecommunication, and interruption throughout the length of the shell. Thiswill make it l,necessary for the circulating fluid to change itsdirection between each of the baille-plates 28 and thus t'o partiallycircui ribe. the various tubes as the viscous liqui proceeds along itspath of travel. Other arrangements of openings of different dimensionsand shape could also be used to advantage under certain onditions. Itwill, therefore, be evident that due to the uniform distribution ofcirculating orifices -throughout the baille plate thatl a uniformdistribution of the viscbusfluid will take place over t-he surface ofthe tubes 31. Maximum tubulency will be obtained due to the inversion ofthe jets, especially through the peculiar triangularshaped orifices; thehigh velocity attained by the .fluid as it passes through these orificesand the acceleration and retardation of flow \due' to the change of thejet, as italternately 'passesl throu h one baille-plate .and strikes thewall por ion of the next baille-plate. 130.y

In operation of the present invention, it will be understood that onefluid passes in through the connection 19 and thence from the drinn 15through the tubes in the shell compartment 23. When this fluid reachesthe opposite end of the shell, it then passes to the other set of tubesby Way of the tube sheet cap 33 and returns to the outlet passageway 20through the tubes in compartment 24. At the same time, another fluid ispassing into the shell through the connection 21 and along thecompartment 24 tov the shell cap,from which. point it flows into thecompartment 23 and returns to the outlet connection 22. During this flowthe fluid will pass through-.alined orifices 32 in the alternatebail-plates, said orifices as before explained being preferablystaggered in relation to each other on alternate bafiles. IIhiscondition is'brought about by the reversal of the successive duplicatebaffleplates which will cause' the various jets of liquid to deviateslightly from theirjdirect course of travel and wipe the sides of thetubes. This deviation will produce a minimum friction loss, as comparedto other ltypes of heat exchangers, in which vlarge openings have"beenused without obtaining turbulence and in which instance the spacing ofthe openings has been such as to make it necessary for the liquid toflow along the sidewalls of the shell and baffles. This action would, ofcourse,increase the friction losses, which are materially reduced in thepresent instance by the slight variation in.

the direction of the flow throughout the length of the tubes and thehigh degree of localized turbulence obtained without increased skinfrict-ion along ineffective surfaces.

It will thus be seen that by the use of the present, structure amaximum' turbulence will be produced, which action will bev localizedbetween and around the various pipes and longitudinally of the shell andwill be practically uniform in its effect upon all of the tube surfacesf`This is in contradistinction to most of the present heat exchangers inwhich the turbulence in them decreases as the area of the passageincreases. This is, of course, due to the fact that considerable of thefluid has passed over other surfaces than the tubes. In the present caseturbulency is accompanied by a high velocity flow of the liquid throughthe orifices, a maximum distribution of the liquid over the surfaces ofthe tubes and a. minimum friction loss due to the slight deviation oftravel of the jets through the shell. It is apparent that any friction.loss due to disturbance at the tube surface is beneficial, as it Vis thefriction loss due to'the travelover the surface of the baffles and sheetwhich is detrimental, and 'this has been reduced to a minimum in thepresent invention.

While I have shown the preferred form of my invention, as now known tome, it will be understood that various changes in the combination,construction and arrangement of parts/may be made by those skilled inthe art, without departing from the spirit of the invention, as claimed.

Having thus described my invention, what I claim and desire to secure byLetters Patent is 1. A heat exchanger comprising an outer shell, aplurality of transverse baille plates therein disposed in spacedrela-tion to each other, said plates each being formed with a pluralityof perforations other than the perforations for the tubes, theperforations ofl adjacent plates being staggered relative to each other,and a set of tubes extending longitudinally of the shell and through theplates.

2. A heat exchanger comprising an outer shell, a. set of tubes extendinglongitudinally of the shell, a plurality of transverse baiiie platesdisposed in spaced relation to each other within the shell and throughwhich the tubes extend, said plates each being formed with a pluralityof perforations disposed intermediate groups of the tubes.

3. A heat exchanger comprising a shell through which a fluid is to flow,a nest of tubes within said shell and through which another fluid mayflow and a plurality of transverse baffle walls, through which the tubesmay extend, said walls being formed with systematically arrangedopenings between adjacent groups of pipes, whereby the flow of the fluidwithin the shell will be subdivided into a plurality of turbulent jetspassing along and around the tubes.

4. A baille-plate for a he-at exchanger of the plural tube type,characterized by the provision of tubereceiving openings symmetricallyarranged with respect to a median line, and additional openingsstaggered with Vrespect to similar yopenings on the opposite side ofsaid median line.

5. A baffle-plate for a heat exchanger of. the plural tube type,characterized by the provision of rounded corner triangular holes,

l eaoh of said rounded corners being of such size as to receive one ofthe tubes'.

6. A baffle-plate for a heat'exchanger of the plural tube type,characterized by the provision of tube-receiving openings and additionalopenings merginginto certain of said tube-receiving openings, saidadditional `openings being staggered with respect to a median line,extending longitudinally of the shell.

7 In a heat exchanger, an outer shell, a plurality of transversebaiiie-plates in said outer shell, a longitudinal partition memberibetween each pair of baffle-plates, and means for securing saidbaille-plates and said par- 'titionsfin position in said outer shell.

'How of fluid through said tubes, means for establishing a flow of fluidthrough the shell and around the tubes, and baflles haying openingswhereby the fluid Howin through the shell will be reourrently directetowards a plurality of tubes at high velocity and interrupted byintermediate periods of 10 fluid tlow at, decreased velocities.

In testimony whereof I have hereunto set y hand in the presence of twosubscribing wltnesses.

CARL F. BRAUN.

Witnesses:

H. S. HoUeH'roN, AC. H. SnA'rrUoK.

